Hi all,
I have some thoughts on the implementation of ALTO servers and I'd like
to get some feedback on the idea.
The basic functionalities of an ALTO server are:
- Collecting data from the information sources;
- Publishing the information to clients (using ALTO protocol).
While the latter is well-defined in RFC 7285, there are no standards for
the communication between an ALTO server and information sources. There
are three scenarios:
- The ALTO server is deeply embedded into the information source, just
like what we are trying to do in Open Daylight.
- The ALTO server is partially embedded into the information source.
For example, in the early stage of out implementation in ODL, we used an
external server which pulls data from ODL using RESTCONF and converts
them into RFC7285-compatible formats.
- The ALTO server is decoupled from the information source.
It is for the last scenario that a standard protocol might be helpful.
To get started, I can think of two basic and probably most common
implementation choices, and they both can have multiple different
information sources:
- End-to-End:
The server builds its maps using an full-mesh internal
representation. This can happen if the server is using end-to-end
measurement methods or it just doesn't have the priority to fetch
topology information.
- Topology-based:
In this case the server is using a graph representation and there can
be some internal nodes besides endpoints. A server can fetch topology
view directly, either from configurations or by making a query to a SDN
controller. Also one can use aggregated data such as the inferred AS graph.
Accordingly we can identify the following kinds of information for both
implementation choices:
- Connection-based statistics;
- Link-based statistics;
- (?) Node-based statistics.
All three statistics can be encapsulated using the following JSON
representation:
{
/* the type of the statistics */
'type': 'alto-IS-e2e',
/* choices: alto-IS-e2e, alto-IS-link, alto-IS-node, etc. */
/* identity for the provider of the information */
'source': 'grid-ftp-client:ef423dab',
'data': [
{
'meta': {
/* e2e */
'src': 'ipv4:X.X.X.X',
'dst': 'ipv4:Y.Y.Y.Y',
/* link */
'id': 'e15',
/* node */
'id': 'n02'
},
'statistics': [
/* e2e */
'average-round-trip-time': '10ms',
'average-drop-rate-percentage': '5',
...,
/* link */
'status': 'up',
'capacity': '10Gbps',
'available-bandwidth': '5Gbps',
...,
/* node */
...
/* actually I don't have any statistics for nodes in
mind */
]
},
...
]
}
There are also considerations on push/pull modes, integration to IRD and
potential DDoS threats but I'd like to hear some feedback on the
proposal from you alto guys.
Thanks!
Regards,
Kai
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